POSTOPERATIVE CARE AND FOLLOW-UP

As a principle, the ankle should be protected post- operatively against uncontrolled movements to pro- mote wound healing and to permit stable bone ingrowth to the implants. The design of the ankle, implantation technique, additional surgeries, and associated foot disorders may each play a significant role in determining the postoperative regimen. This section summarizes the author’s postoperative treatment concept.

9.1 Postoperative Care

Weight-bearing to tolerance is begun on the first postoperative day, with intermittent elevation when nonambulatory. When the wound condition is suit- able, typically after two to four days, the initial short leg splint is replaced by a brace (Vacuped ^® , Oped, Cham, Switzerland; Fig. 9.1) that protects the ankle against eversion, inversion, and plantar

Fig. 9.1. Vacuped

.

The Vacuped

(oped, Cham, Switzerland) is available in three sizes. As the vacuum is applied, the air cushion is stabilized while maintaining a proper and stable fit to the foot and ankle (see text)

Fig. 9.2. Short weight-bearing cast.

Short weight-bearing casts were used for this patient (female, 66 years, second postoperative day) because of lateral ligament reconstruction on both ankles during bilateral total ankle replacement. These temporary casts with anterior openings (a) allow for some weight-bearing (b), but will be replaced by stronger, circular casts when local swelling is gone

a b

flexion movements for six weeks. For patients with poor bone quality, and/or who have undergone addi- tional surgeries such as realignment, ligament reconstruction, and/or joint fusions, a short weight- bearing cast (Fig. 9.2) is used for six weeks, and a brace is used for an additional four to six weeks.

Stable shoes and support stockings are then recom- mended for two to six months until the swelling has subsided and ankle strength has returned. There- after, comfortable footwear is worn during activities of daily living. Custom-molded shoes or corrective orthotic insoles may be prescribed for associated complex foot disorders.

9.2 Rehabilitation Program

A stretching program is commenced immediately after surgery. The patient is asked to bear as much load as possible on the operated foot, and then to bring the knee successively anteriorward until the heel starts to lift up off of the floor (Fig. 9.3). The patient is advised to perform this exercise once or twice a day. Lymphatic drainage is started after removal of the sutures, usually two weeks after sur- gery. If a short leg cast is used, lymphatic drainage and stretching exercises are started after removal of the cast. Active range-of-motion exercises are begun six weeks after surgery. The rehabilitation program additionally includes exercises to improve muscular strength and muscular control of foot movement, with gradual return to full activities as tolerated.

9.3 Follow-up Examination

Regular clinical and radiological controls may help to identify problems at an early stage, and thus prevent failures. To date, the author sees his post- operative patients at six weeks, at four months, and at one year, and yearly thereafter for clinical and radiological control. An extensive standardized pro- tocol is used at one year, and thereafter for each yearly control.

9.3.1 Clinical Assessment

Patients are asked to indicate their current level of function (as compared with preoperative function) in activities of daily living and in specific activities (sports and climbing stairs, for example) (Table 9.1), as well as their level of satisfaction with the pro- cedure.

The clinical examination includes a careful assessment of the alignment of the ankle with the patient standing, and the range of motion and stability of the ankle with the patient sitting and standing. The range of motion is determined clini- cally using a goniometer along the lateral border of the leg and foot. Alignment, stability, and motion are compared with the uninvolved side.

The patient then is asked to rate his or her pain on a scale of 0 to 10 points, with no pain giving 0 points, and maximal pain giving 10 points. Then the AOFAS Hindfoot Score is calculated [3].

Fig. 9.3. Stretching program.

The knee is brought anteriorward (knee flexion) until the heel starts to lift up off of the floor

(female, 49 years, second postoperative day; see text)

9.3.2 Radiographic Measurements

Postoperative radiographic examinations are best taken with the aid of fluoroscopy in order to obtain standardized and true anteroposterior and lateral views of both components. Image intensification is used to obtain straight anteroposterior and lateral views of the tibial component. This allows the eval- uation of migration or loosening on serial radio- graphs (Fig. 9.4).

Angular and linear values are defined to delineate alignment and component migration (Fig. 9.5: α- angle, β-angle, γ-angle, distances “a” and “b,” dia- meter of potential lysis) and measured digitally with a special metric software system (Imagic Access ^® , PIC Systems AG, Glattbrugg, Switzerland).

Loosening of the tibial component is defined as a change in position of greater than 2° of the flat base of the component in relation to the long axis of the tibia. For example:

– with the HINTEGRA ^® ankle [2]; angles “a” and

“b” in Fig. 9.5b, and/or as a progressive radio- lucency of more than 2 mm in either the antero- posterior or the lateral view, and

– with the S.T.A.R. ankle [1, 4]; angles “a” and “b”

in Fig. 9.6b, and/or as a subsidence into the tibial

bone of greater than 2 mm (distance “a” in Fig.

9.6a).

Loosening of the talar component as seen on the lateral radiograph is defined as subsidence into the talar bone of greater than 5 mm. For example:

– with the HINTEGRA ^® ankle [2]; distances “a” and

“b” in Fig. 9.5b, or a change in position of greater than 5° relative to the line drawn from the top of the talonavicular joint to the tuberosity of the calcaneus (angle γ in Fig. 9.5b), and

– with the S.T.A.R. ankle [1, 4]; distances “b” and

“c” in Fig. 9.6b, or a change in position of greater than 5° relative to the line drawn from the top of the talonavicular joint to the tuberosity of the calcaneus (angle γ in Fig. 9.6b).

Evaluation of a minor change in position of the talar component on the anteroposterior radiograph is very difficult, and it is not possible to evaluate radiolucencies beneath the talar component on either view.

True foot and ankle motion are measured by lateral views under fluoroscopy, while the patient is standing on a footplate (Fig. 9.7). The footplate is plantar flexed and dorsiflexed as much as possible, until the tibia tends to follow foot motion.

Table 9.1. Clinical score

Grade Pain Limitation of Limitation Requirement Wearing of

Recreational of Daily for Support Fashionable

Activities Activities Shoes

Excellent None None None None Yes

Good Mild, occasional Some None None Some

Fair Moderate, frequent Yes Yes One cane None

Poor Severe, nearly always Severe Severe Walker or brace Orthopedic shoes

Fig. 9.4. Standardized radiographs.

Post-traumatic osteoarthrosis after ankle fracture (male, 59 years, smoker): Standardized anteroposterior and lateral views (a) are obtained using image intensification to show the position of the implants and the bone-implant interface similarly for all follow-up controls (b–h)

a b c d

e f g h

Fig. 9.5. Reference lines – HINTEGRA

ankle.

The following reference lines and angles are used to evaluate stability and loosening of the tibial and talar components [2]:

a: α = the angle, on anteroposterior view, between the longitudinal axis of the tibia and the articulating surface of the tibial component;

b: β = the angle, on lateral view, between the longitudinal axis of the tibia and the articulating surface of the tibial component; γ = the angle, on lateral view, between a line drawn through the anterior shield and the posterior edge of the talar component and a line drawn between the dorsal aspect of the talonavicular joint and the tuberosity of the calcaneus; “a” = the perpendicular distance, on lateral view, from the most anterior part of the talar component to a line drawn between the dorsal aspect of the talonavic- ular joint and the tuberosity of the calcaneus; and “b” = the perpendicular distance, on lateral view, from the most posterior part of the talar component to the same line described under “a” (female, 43 years; two-year follow-up)

Fig. 9.6. Reference lines – S.T.A.R. ankle.

The following reference lines and angles are used to evaluate stability and loosening of the tibial and talar components [1, 4]:

a: α = the angle, on anteroposterior view, between the longitudinal axis of the tibia and the articulating surface of the tibial component; “a” = the perpendicular distance, on anteroposterior view, between the tip of the lateral malleolus and a line drawn through the base of the tibial component;

b: β = the angle, on lateral view, between the longitudinal axis of the tibia and the articulating surface of the tibial component; γ = the angle, on lateral view, between a line drawn through the anterior shield and the posterior edge of the talar component and a line drawn between the dorsal aspect of the talonavicular joint and the tuberosity of the calcaneus; “b” = the perpendicular distance, on lateral view, from the most anterior part of the talar component to a line drawn between the dorsal aspect of the talonavicular joint and the tuberosity of the calcaneus; and “c” = the perpendicular distance, on lateral view, from the most posterior part of the talar component to the same line described under “a” (male, 52 years; five-year follow-up)

a b

a b

9.4 Conclusions

The replaced ankle should be protected postopera- tively against uncontrolled movements to promote wound healing and to permit stable bone ingrowth to the implants. Most implants allow for weight- bearing, as tolerated, within one to two weeks after surgery. As a principle, the main rehabilitation program starts after six weeks, including stretching exercises, lymphatic drainage, active range-of- motion exercises, and exercises to improve muscular strength and muscular control of foot movement, with gradual return to full activities as tolerated.

Regular clinical and radiological controls may help to identify problems at an early stage, and thus prevent failures. A standardized clinical and radiographic examination is recommended.

References

[1] Anderson T, Montgomery F, Carlsson A (2003) Uncement- ed S.T.A.R. total ankle prosthesis. Three to eight-year follow-up of fifty-one consecutive ankles. J Bone Joint Surg Am 85: 1321–1329

[2] Hintermann B, Valderrabano V, Dereymaeker G, Dick W (2004) The HINTEGRA ankle: rational and short-term results of 122 consecutive ankles. Clin Orthop 424: 57–68 [3] Kitaoka HB, Alexander IJ, Adalaar RS, Nunley JA, Myer-

son MS, Sanders M (1994) Clinical rating systems for the ankle-hindfoot, midfoot, hallux, and lesser toes. Foot Ankle Int 15: 349–353

[4] Valderrabano V, Hintermann B, Dick W (2004) Scandina- vian total ankle replacement: a 3.7-year average follow-up of 65 patients. Clin Orthop 424: 47–56

Fig. 9.7. Foot and true ankle motion.

Radiographs show range of motion as measured for plantar flexion (a) and dorsiflexion (b). “True ankle motion” (the motion within the prosthetic system), and

“foot motion” (the total motion of the hindfoot with respect to the tibial long axis – dashed lines) (male, 68 years; one-year-follow-up)

a b